Sensors and Actuators B 190 (2014) 990–998 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal h om epage: www.elsevier.com/ locate/snb Copper phthalocyanine/single walled carbon nanotubes hybrid thin films for pentachlorophenol detection Hikmat Banimuslem a , Aseel Hassan a , Tamara Basova b,∗ , Asuman Dako˘ glu Gülmez c , Sinem Tuncel c , Mahmut Durmus ¸ c , Ays ¸ e Gül Gürek c , Vefa Ahsen c,d a Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB, UK b Nikolaev Institute of Inorganic Chemistry, Department of chemistry of coordination, cluster and supramolecular compounds, SB RAS, 3 Lavrentiev Ave. 630090 Novosibirsk, Russia c Gebze Institute of Technology, Department of Chemistry, Gebze, Kocaeli, Turkey d TUBITAK-Marmara Research Center, Materials Institute, Gebze, Kocaeli, Turkey a r t i c l e i n f o Article history: Received 11 June 2013 Received in revised form 29 August 2013 Accepted 11 September 2013 Available online 20 September 2013 Keywords: Phthalocyanine Carbon nanotubes Optical sensors Pentachlorophenol Thin films Ellipsometry a b s t r a c t Tetra-substituted copper phthalocyanine (CuPcR 4 , R = -S(CH 2 ) 15 CH 3 ) has been prepared and charac- terised by UV–Vis, FT-IR and mass-spectrometry. Hybrid materials were produced by mixing CuPcR 4 with acidified single-walled carbon nanotubes (SWCNTs) and characterised by UV–Vis absorption spec- troscopy, scanning electron microscopy and atomic force microscopy. Thin films of pristine CuPcR 4 and SWCNT/CuPcR 4 were prepared by spin coating onto gold-coated glass slides and applied as active layers to detect pentachlorophenol (PCP) in water utilizing total internal reflection ellipsometry (TIRE) tech- nique. Different concentrations of PCP in water ranging from 0.5 to 10 g/l have been examined in the current work. It is revealed that the phase shift (()) spectra of SWCNT/CuPcR 4 films were two times larger than the shifts produced by the pristine CuPcR 4 films with clear recovery in the () spectra after flushing the cell with water. The adsorption of PCP on both types of films is discussed and films’ sensitivity was determined using the change in films’ refractive index. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The worldwide use of pesticides and herbicides for agricultural purposes is classified as a global environmental pollution problem. Herbicides used in agriculture can easily take way to surface or ground waters, possibly causing adverse ecotoxicological effects on aquatic life and changing drinking water quality [1]. Chlorophenols represent a major group of pollutants of environmental concern. Due to their wide spreading and toxic properties, some chlorinated phenols, such as pentachlorophenol (PCP), 2-chlorophenol, 2,4- dichlorophenol, and 2,4,6-trichlorophenol (2,4,6-TCP) have been considered as priority pollutants. PCP is the most toxic represen- tative of the chlorophenols and an important organic chemical for environmental studies because of its common application in agri- culture, industry and commercial product synthesis [2]. It is highly toxic and persistent in water and soil. Concentrations of PCP ran- ging from trace levels to 10,500 g/l in various surface waters from different countries have been reported by the World Health Orga- nization [3]. Furthermore, it can accumulate in living organisms ∗ Corresponding author. Tel.: +7 383 3302814; fax: +7 383 3309489. E-mail addresses: basova@niic.nsc.ru, tbasova@mail.ru (T. Basova). and result in negative effects, including carcinogenicity and acute toxicity. Different analytical procedures based on liquid chromatography–mass spectrometry (LC–MS) [4–6], LC–tandem mass spectrometry (LC–MS/MS) [7], high performance liquid chromatography (HPLC) [8], and gas chromatography–mass spec- trometry (GC–MS) [9] have been reported to provide efficient determination of these pesticides, according to the present leg- islation. However these methods, although highly sensitive and specific, are quite laborious, time-consuming, and expensive, and not suitable for on-site applications. There is therefore continuous demand for highly sensitive, cost-effective, rapid and portable detection methods which at the same time can meet international legislation allowed levels of PCP and other toxic compounds. Ellipsometry can be used in total internal reflection (TIRE) mode and in combination with the surface plasmon resonance phenomenon for sensing aspects [10–12]. There has been exten- sive work in applying TIRE as a technique for the detection of biomolecules [13,14]. It was established that TIRE is a more suitable technique than SPR method for the registration of low molecu- lar weight toxins such as simazine, atrazine and T2 mycotoxin [15]. TIRE technique has attracted substantial attention because of its fast response, simple instrumentation, being non-destructive 0925-4005/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.snb.2013.09.059